1. Field of the Invention
The present invention relates to pyrometallurigal processing, including a process and apparatus for producing metal chlorides and metals from material having a metal oxide content, such as the adjacent rock strata of coal seams, or from industrial sources, such as solid byproducts of industrial plants.
2. Background Information
Historically, some metals for the metal working industry are produced from ores, which can contain high weight percentages, such as more than 50 wt. % of a metal oxide of interest (high-grade sources). Iron is generally produced from hematite (Fe2O3) or magnetite (Fe3O4), aluminum from bauxite (Al2O3) and titanium from rutile (TiO2) or ilmenite (FeTiO3). Their saturated content and the fact that most of these ores bear only one metal oxide making isolation and purification simple, made these ores the source of first choice for the metal working industry.
Nevertheless, metal oxides are present in all kinds of natural sources, e.g., geological minerals such as igneous, sedimentary or metamorphic rock material or from man-made sources such as industrial waste material. These sources however have a metal oxide content of less than 50 wt %, and are often present in a mix of various metal oxides. Low metal oxide content and high content of undesired silicates and other impurities caused their economical designation as waste. For example, the adjacent rock strata in coal mining describes material that lies above or below the coal seam; usually comprising of rock with some coal. During coal mining, some of the undesired adjacent rock strata is unearthed as well. This material is usually deposited as coal mine waste above ground covering vast areas of landscapes. Typically, coal mine waste comprises carbonaceous material (coal, tar, etc.) and rock material of metaliferous content, including aluminum oxides, iron oxides, titanium oxides, and other metal oxides depending on the geological nature of the adjacent rock strata. Generally, the total weight percentage of metal oxides in coal mine waste ranges between 15 and 30 wt. % of the coal mine waste. In the past, these amounts were too low to economically consider coal mine waste as a source for metal chlorides or elemental metals. The same holds true for metal oxide containing material from industrial sources such as the ash from coal fired power plants, which—due to their geological origin also have a weight percentage of metal oxides between 25% and 35%.
U.S. Pat. No. 6,808,695 B1 discloses a process for continuously producing aluminum from clays, such as kaolinite, illite or siliceous bauxite. U.S. Pat. No. 4,349,420 describes a process of fractional condensation/distillation for the production of aluminum chloride.